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Instead of setting RLIMIT_NPROC to unlimited when sudo initializes,

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just save RLIMIT_NPROC in exec_setup() before the final setuid()
and restore it immediately after.  We don't need to modify RLIMIT_NPROC
for simple euid changes, just for changing the real (and saved)
uids before we exec.  This also means we no longer need to worry
about _SC_CHILD_MAX returning -1.  Bug #565
This commit is contained in:
Todd C. Miller
2013-07-29 15:34:49 -06:00
parent b1c8f0575b
commit 3582ad3409
1 changed files with 51 additions and 47 deletions
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98
src/sudo.c
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@@ -133,8 +133,8 @@ static void iolog_unlink(struct plugin_container *plugin);
#ifdef RLIMIT_CORE
static struct rlimit corelimit;
#endif /* RLIMIT_CORE */
#if defined(__linux__)
#endif
#ifdef __linux__
static struct rlimit nproclimit;
#endif
@@ -824,26 +824,10 @@ sudo_check_suid(const char *path)
static void
disable_coredumps(void)
{
#if defined(__linux__) || defined(RLIMIT_CORE)
#if defined(RLIMIT_CORE)
struct rlimit rl;
#endif
debug_decl(disable_coredumps, SUDO_DEBUG_UTIL)
#if defined(__linux__)
/*
* Unlimit the number of processes since Linux's setuid() will
* apply resource limits when changing uid and return EAGAIN if
* nproc would be violated by the uid switch.
*/
(void) getrlimit(RLIMIT_NPROC, &nproclimit);
rl.rlim_cur = rl.rlim_max = RLIM_INFINITY;
if (setrlimit(RLIMIT_NPROC, &rl)) {
memcpy(&rl, &nproclimit, sizeof(struct rlimit));
rl.rlim_cur = rl.rlim_max;
(void)setrlimit(RLIMIT_NPROC, &rl);
}
#endif /* __linux__ */
#ifdef RLIMIT_CORE
/*
* Turn off core dumps?
*/
@@ -853,8 +837,46 @@ disable_coredumps(void)
rl.rlim_cur = 0;
(void) setrlimit(RLIMIT_CORE, &rl);
}
#endif /* RLIMIT_CORE */
debug_return;
#endif /* RLIMIT_CORE */
}
/*
* Unlimit the number of processes since Linux's setuid() will
* apply resource limits when changing uid and return EAGAIN if
* nproc would be exceeded by the uid switch.
*/
static void
unlimit_nproc(void)
{
#ifdef __linux__
struct rlimit rl;
debug_decl(unlimit_nproc, SUDO_DEBUG_UTIL)
(void) getrlimit(RLIMIT_NPROC, &nproclimit);
rl.rlim_cur = rl.rlim_max = RLIM_INFINITY;
if (setrlimit(RLIMIT_NPROC, &rl) != 0) {
memcpy(&rl, &nproclimit, sizeof(struct rlimit));
rl.rlim_cur = rl.rlim_max;
(void)setrlimit(RLIMIT_NPROC, &rl);
}
debug_return;
#endif /* __linux__ */
}
/*
* Restore saved value of RLIMIT_NPROC.
*/
static void
restore_nproc(void)
{
#ifdef __linux__
debug_decl(restore_nproc, SUDO_DEBUG_UTIL)
(void) setrlimit(RLIMIT_NPROC, &nproclimit);
debug_return;
#endif /* __linux__ */
}
/*
@@ -975,6 +997,12 @@ exec_setup(struct command_details *details, const char *ptyname, int ptyfd)
}
}
/*
* Unlimit the number of processes since Linux's setuid() will
* return EAGAIN if RLIMIT_NPROC would be exceeded by the uid switch.
*/
unlimit_nproc();
#ifdef HAVE_SETRESUID
if (setresuid(details->uid, details->euid, details->euid) != 0) {
warning(_("unable to change to runas uid (%u, %u)"), details->uid,
@@ -995,6 +1023,9 @@ exec_setup(struct command_details *details, const char *ptyname, int ptyfd)
}
#endif /* !HAVE_SETRESUID && !HAVE_SETREUID */
/* Restore previous value of RLIMIT_NPROC. */
restore_nproc();
/*
* Only change cwd if we have chroot()ed or the policy modules
* specifies a different cwd. Must be done after uid change.
@@ -1009,33 +1040,6 @@ exec_setup(struct command_details *details, const char *ptyname, int ptyfd)
}
}
/*
* SuSE Enterprise Linux uses RLIMIT_NPROC and _SC_CHILD_MAX
* interchangably. This causes problems when setting RLIMIT_NPROC
* to RLIM_INFINITY due to a bug in bash where bash tries to honor
* the value of _SC_CHILD_MAX but treats a value of -1 as an error,
* and uses a default value of 32 instead.
*
* To work around this problem, we restore the nproc resource limit
* if sysconf(_SC_CHILD_MAX) is negative. In most cases, pam_limits
* will set RLIMIT_NPROC for us.
*
* We must do this *after* the uid change to avoid potential EAGAIN
* from setuid().
*/
#if defined(__linux__) && defined(_SC_CHILD_MAX)
{
struct rlimit rl;
long l;
errno = 0;
l = sysconf(_SC_CHILD_MAX);
if (l == -1 && errno == 0 && getrlimit(RLIMIT_NPROC, &rl) == 0) {
if (rl.rlim_cur == RLIM_INFINITY && rl.rlim_max == RLIM_INFINITY)
(void) setrlimit(RLIMIT_NPROC, &nproclimit);
}
}
#endif
rval = true;
done: